Our goal is to develop electrochemical sensors for amperometric detection of clinically important compounds. The liquid chromatography in conjunction with electrochemistry (LCEC) is an excellent combination to enhance the selectivity and sensitivity of detection. It is necessary to use highly sensitive methods for detection of clinically important compounds because they are usually present in minute amounts of mixtures. First, electrochemical and chromatographic experiments will be conducted independently prior to LCEC. Cyclic voltammetry is the first experiment to perform in the laboratory for electrochemical characterization of the sample. The best electrode modification procedure will be determined and the oxidation or reduction potential of the substance(s) to be analyzed will be estimated from voltammetric measurements. Amperometric experiments will then be performed at the pre-determined potential. Voltammetric and amperometric techniques are valuable because they will lead to optimize parameters such as potential to be applied, type of the working electrode, supporting electrolyte, and flow rate. In addition, cyclic voltammetry is an excellent tool for investigation of electron/charge transfer mechanisms at the electrode surface. Liquid chromatographic experiments will be performed in parallel to electrochemical experiments. Pure samples as well as mixtures will be used and column conditions will be optimized. After optimization of liquid chromatographic conditions for separation and electrochemical parameters for detection, chromatographic columns and the electrochemical detector will be coupled for LCEC experiments. Sensitivity of detection, and lower and upper detection limits will then be determined for each analyte.